In Wrath of the Lich King it is item level 251 and requires level 80. In MoP Classic it is item level 251, requires level 80 and sells to vendors for 1c.
Read from the World of Warcraft client build files.
How Relentless Gladiator's Satin Mantle Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Relentless Gladiator's Satin Mantle suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Similar Items
The 10 items nearest to Relentless Gladiator's Satin Mantle (item level 35) in item level among Armor > Cloth, Shoulder slot, from item level 31 to 38.
Items Numbered Next to Relentless Gladiator's Satin Mantle
Blizzard numbers items as they are created, so the named items next to ID 41935 (41930 to 41941) were usually added in the same batch as Relentless Gladiator's Satin Mantle: the same quest line, zone, vendor or reward set.